The 87-year-old actor reportedly died of natural causes at Juravinski Hospital in Hamilton, Ontario.
Frid was best known for playing vampire Barnabas Collins on gothic television soap opera Dark Shadows.
The series originally aired on ABC in the US between June 1966 and April 2, 1971.
Frid also starred in 1973 television movie The Devil's Daughter and 1974 film horror Seizure.
He filmed a cameo appearance - his final acting credit - in Tim Burton's forthcoming film remake of Dark Shadows, which stars Johnny Depp as Barnabas.
Depp previously admitted to being "obsessed" as a child with Frid's performance as the 200-year-old vampire.
"I loved the show when I was a kid [and] I was obsessed with Barnabas Collins," the Hollywood star said in 2009. "I have photographs of me holding Barnabas Collins posters when I was 5 or 6."
> Johnny Depp: 'Dark Shadows is a classic vampire film'
Watch Jonathan Frid in a clip from the original Dark Shadows below: